Quantum uncertainty, and Schrodinger's cat

[fromderinside]

Someone explain to me again how the detector, which observes whether the atom decayed, does not detect whether the atom decays and collapse the state of the whole system...

What detector? How would you know that a putative detector inserted inside the box detected something if not by opening the box, which would then collapse everything if it wasn't already done. So, you couldn't tell when it collapsed. I think this is the problem of insisting on a realist interpretation when by design any observer has to wait outside the box till the box opens, at which point he can't tell when exactly the waves collapsed.
EB

When the detector in the box detects the decay the experiment is over. Who gives a shit about an outside observer? Irrelevant.

 

[Speakpigeon]

What detector? How would you know that a putative detector inserted inside the box detected something if not by opening the box, which would then collapse everything if it wasn't already done. So, you couldn't tell when it collapsed. I think this is the problem of insisting on a realist interpretation when by design any observer has to wait outside the box till the box opens, at which point he can't tell when exactly the waves collapsed.
EB

When the detector in the box detects the decay the experiment is over. Who gives a shit about an outside observer? Irrelevant.

Not irrelevant to the observer outside the box, which was my point...

Schrodinger’s thought experiment was intended to show the absurdity of that interpretation. However, the supporters of the interpretation said that, since the state of the cat was solely dependent on the state of the decay process, the state of the cat was entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the cat’s state is entangled with it, the cat’s state is in all possible states, a state of entangled superposition.

Let me translate that for the hard of hearing:

... since the state of the camera is solely dependent on the state of the decay process, the state of the camera is entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the camera’s state is entangled with it, the camera’s state is in all possible states, a state of entangled superposition.​

EB

 

[Speakpigeon]

I have to disagree.

When we take a measurement, it's not the scientist that is the observer, it's the measuring device. The measuring device is interacting with whatever it is you're measuring, and that's what causes the collapse of the wave function. The scientist reading the dial is not what causes the collapse of the wave function. So in the Schrodinger's cat example, once a quantum state starts a chemical reaction in the petri dish, then the damn petri dish is the measuring device that causes the collapse of the wave function. By the time the chemical reaction starts, the chain of events has entered the macroscopic world. The person opening the box is the equivalent of a scientist looking at a dial on a measuring device.

I would love to know what exactly can be an "observer", and how it makes it's "observations".

How does something observe when it has no eyes?

Are we twisting the definition of "observer"?

I think early QM scientists started with a proper observer (them ) but then generalised the notion to measurement and further to interaction. As I understand it, each term suits some scientists but not others.

So the term used may hint at a particular philosophical position.
EB

 

[Juma]

When the detector in the box detects the decay the experiment is over. Who gives a shit about an outside observer? Irrelevant.

Not irrelevant to the observer outside the box, which was my point...

Schrodinger’s thought experiment was intended to show the absurdity of that interpretation. However, the supporters of the interpretation said that, since the state of the cat was solely dependent on the state of the decay process, the state of the cat was entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the cat’s state is entangled with it, the cat’s state is in all possible states, a state of entangled superposition.

Let me translate that for the hard of hearing:

... since the state of the camera is solely dependent on the state of the decay process, the state of the camera is entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the camera’s state is entangled with it, the camera’s state is in all possible states, a state of entangled superposition.​

EB

No. Large entagled states require very special circumstances.

 

[DBT]

What is an example of a large entangled state in terms of macro scale objects?

 

[skepticalbip]

What is an example of a large entangled state in terms of macro scale objects?

There is likely no such thing as a cat being in an entangled state (I wouldn't say absolutely in no circumstance because the universe actually is stranger than we can imagine). That is the reason it is a thought experiment. There is no such thing as a person riding on a photon to see what the universe looks like from that perspective either but that is the thought experiment that formed the basis of Einstein's relativity. Thought experiments can tell us a lot about reality even though they are not, and can not be, actually be conducted.

There is no problem if you don't like the Copenhagen interpretation. Many physicists don't like it either. But they have other reasons than that it isn't what we see in everyday life.

 

[Speakpigeon]

Not irrelevant to the observer outside the box, which was my point...

Schrodinger’s thought experiment was intended to show the absurdity of that interpretation. However, the supporters of the interpretation said that, since the state of the cat was solely dependent on the state of the decay process, the state of the cat was entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the cat’s state is entangled with it, the cat’s state is in all possible states, a state of entangled superposition.

Let me translate that for the hard of hearing:

... since the state of the camera is solely dependent on the state of the decay process, the state of the camera is entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the camera’s state is entangled with it, the camera’s state is in all possible states, a state of entangled superposition.​

EB

No. Large entagled states require very special circumstances.

Blah-blah-blah. It's a thought experiment.

A camera wouldn't be in any way "larger" than a cat, dead or alive. Nowadays it could be smaller. We could make it even smaller. Maybe just a detector and recorder "cat dead/cat alive" with the time. Say no to the camera and you have to say no to the cat (and to Schrödinger).



Also, I already alluded to Nicolas Gisin's (2011?) experiment in Geneva where two macroscopic bits of neodymium crystals (10⁶ atoms) were effectively entangled. That's very small but the principle is quite simple and if I understand it the condition is to keep the entangled bits isolated from their environment. That may be difficult but I don't why it would so very special.
EB

 

[skepticalbip]

Not irrelevant to the observer outside the box, which was my point...

Schrodinger’s thought experiment was intended to show the absurdity of that interpretation. However, the supporters of the interpretation said that, since the state of the cat was solely dependent on the state of the decay process, the state of the cat was entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the cat’s state is entangled with it, the cat’s state is in all possible states, a state of entangled superposition.

Let me translate that for the hard of hearing:

... since the state of the camera is solely dependent on the state of the decay process, the state of the camera is entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the camera’s state is entangled with it, the camera’s state is in all possible states, a state of entangled superposition.​

EB

No. Large entagled states require very special circumstances.

Blah-blah-blah. It's a thought experiment.

A camera wouldn't be in any way "larger" than a cat, dead or alive. Nowadays it could be smaller. We could make it even smaller. Maybe just a detector and recorder "cat dead/cat alive" with the time. Say no to the camera and you have to say no to the cat (and to Schrödinger).



Also, I already alluded to Nicolas Gisin's (2011?) experiment in Geneva where two macroscopic bits of neodymium crystals (10⁶ atoms) were effectively entangled. That's very small but the principle is quite simple and if I understand it the condition is to keep the entangled bits isolated from their environment. That may be difficult but I don't why it would so very special.
EB

You seem to be confusing entanglement and superposition and to have no idea what the Schrodinger's cat thought experiment is intended to examine.

The thought experiment was set up to have the cat's state totally dependent on the state of the decay process. If the cat's state is totally dependent on the decay state of the radioactive particle, what is the state of the cat during the time that the decay state is in superposition?

How do you have the state of the camera totally dependent (entangled) on the decay state? It isn't. It was intended to "observe" when the decay occurred thus voiding the thought experiment entirely since it provides the condition that the Copenhagen interpretation says is what collapses the wave function. The camera can not "observe" what it was there to "observe" if that purpose prevents the event from happening.
.

 

[fromderinside]

When the detector in the box detects the decay the experiment is over. Who gives a shit about an outside observer? Irrelevant.

Not irrelevant to the observer outside the box, which was my point...

EB

Postulating entanglement for putting a detector in the box is only for the convenience of the observer. Putting a detector in the box does nothing for the observer except to make the observer irrelevant to the experiment. What is hidden needs 'splaining so we 'splain with entanglement. Clear.

Same argument applies to inability to measure even though there are times and places less than those which physically exist. Indeterminacy is simply a method for treating all things equal that can't be measured. Statistics.

 

[Speakpigeon]

Not irrelevant to the observer outside the box, which was my point...

Schrodinger’s thought experiment was intended to show the absurdity of that interpretation. However, the supporters of the interpretation said that, since the state of the cat was solely dependent on the state of the decay process, the state of the cat was entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the cat’s state is entangled with it, the cat’s state is in all possible states, a state of entangled superposition.

Let me translate that for the hard of hearing:

... since the state of the camera is solely dependent on the state of the decay process, the state of the camera is entangled with it. If the quantum uncertainty says that the state of the decay process exists in all possible states (superposition) then, since the camera’s state is entangled with it, the camera’s state is in all possible states, a state of entangled superposition.​

EB

No. Large entagled states require very special circumstances.

Blah-blah-blah. It's a thought experiment.

A camera wouldn't be in any way "larger" than a cat, dead or alive. Nowadays it could be smaller. We could make it even smaller. Maybe just a detector and recorder "cat dead/cat alive" with the time. Say no to the camera and you have to say no to the cat (and to Schrödinger).



Also, I already alluded to Nicolas Gisin's (2011?) experiment in Geneva where two macroscopic bits of neodymium crystals (10⁶ atoms) were effectively entangled. That's very small but the principle is quite simple and if I understand it the condition is to keep the entangled bits isolated from their environment. That may be difficult but I don't why it would so very special.
EB

You seem to be confusing entanglement and superposition and to have no idea what the Schrodinger's cat thought experiment is intended to examine.

No I don't I seem at all.

The thought experiment was set up to have the cat's state totally dependent on the state of the decay process. If the cat's state is totally dependent on the decay state of the radioactive particle, what is the state of the cat during the time that the decay state is in superposition?

No need to show you could explain the idea. I'm not an idiot, I already guessed you could.

How do you have the state of the camera totally dependent (entangled) on the decay state? It isn't.

I certainly didn't say that and I didn't want to say that. I think you are missing something here.

Also, if the cat can be entangled with the radioactive particle why not the camera is what I was asking Juma.

It was intended to "observe" when the decay occurred thus voiding the thought experiment entirely since it provides the condition that the Copenhagen interpretation says is what collapses the wave function.

That a camera should be inside the box to observe (record) the cat doesn't make any substantial difference to the observer outside the box.

I hope you're not saying that the intention of the outside observer to use the camera inside the box would have an effect on entanglement?

I think you are making assumptions beyond the Copenhagen interpretation.

The camera can not "observe" what it was there to "observe" if that purpose prevents the event from happening.

You should have read my post on what would happen to the camera here: When the box is opened, the outside observer would either see a dead cat and a camera having recorded the death of the cat at some point before the opening of the box, or he would see a cat still alive and no recording of a dead cat by the camera. Do you want to disagree with that?


So, if the cat can be entangled with the radioactive particle, why not the camera?
EB

 

[Speakpigeon]

Not irrelevant to the observer outside the box, which was my point...

EB

<snip> Putting a detector in the box does nothing for the observer except to make the observer irrelevant to the experiment.

Are you saying that putting a camera inside the box will change what the guy outside the box will observe on opening the box?

Oh, I see, he will observe that there's not only a cat but also a camera;

What is hidden needs 'splaining so we 'splain with entanglement.

Exactly so.

So now, try reading my post again and it should become clear to you what was the idea.
EB

 

[fromderinside]

<snip> Putting a detector in the box does nothing for the observer except to make the observer irrelevant to the experiment.

Are you saying that putting a camera inside the box will change what the guy outside the box will observe on opening the box?

Oh, I see, he will observe that there's not only a cat but also a camera;

What is hidden needs 'splaining so we 'splain with entanglement.

Exactly so.

So now, try reading my post again and it should become clear to you what was the idea.
EB

Yeah. You struck a moot point. Camera records decay, experiment done, outside observer irrelevant.

 

[Speakpigeon]

Are you saying that putting a camera inside the box will change what the guy outside the box will observe on opening the box?

Oh, I see, he will observe that there's not only a cat but also a camera;

What is hidden needs 'splaining so we 'splain with entanglement.

Exactly so.

So now, try reading my post again and it should become clear to you what was the idea.
EB

Yeah. You struck a moot point. Camera records decay, experiment done, outside observer irrelevant.

Oh noooo! It's not a moot point!! it's essential!!! You can't say that the camera will record decay!!!!

You don't understand how it works at all!!!!! The observer will only discover what happened on opening the box!!!!!! If decay didn't occur I'm pretty sure the camera will not have recorded decay!!!!!!!
EB

 

[WAB]

EB, according to the Chicago Manual of Style, you're only allowed 2 exclamation points per page.

 

[Speakpigeon]

EB, according to the Chicago Manual of Style, you're only allowed 2 exclamation points per page.

There's a manual of style applicable to this forum do you think?

If only posters here could spell properly to begin with...
EB

 

[Kharakov]

What detector? How would you know that a putative detector inserted inside the box detected something if not by opening the box, which would then collapse everything if it wasn't already done. So, you couldn't tell when it collapsed. I think this is the problem of insisting on a realist interpretation when by design any observer has to wait outside the box till the box opens, at which point he can't tell when exactly the waves collapsed.
EB

When the detector in the box detects the decay the experiment is over. Who gives a shit about an outside observer? Irrelevant.

Ehh, if you don't know who won the match, and your buddy hasn't looked, you can still bet based on the knowledge you have. The QM knowledge is simply half-life in this case- if you make it so there is an even 50% chance that the atom decays, you're both idiots for making the bet, even more so for killing a fucking cat to make a bet. That's the relevance.

You don't know until you opened the box. Something definitely happened. The cat is definitely a fucking observer, as is the radiation detector, etc. There is no great fucking mystery- although maybe the universe, spacetime, God, or someone else reserves the right to choose paths 'til the last possible second.

 

[Jesse]

As I understand it, in quantum physics if you make a statement like "the system must be either in state A or B at time T, we just don't know which one", the demonstration that you're wrong can only happen in a situation where you measure the system at some later time T', and the result is such that you retroactively can't be sure whether it was in A or B at the earlier time T. In that case, the rules of probability would say that if really was in state A or B at time T, then the total probability of finding it in state C when you measure it at the later time T' would be given by:

P(system in state C at time T') = P(system in state C at time T', given that it was in state A at time T)*P(system in state A at time T) + P(system in state C at time T', given that it was in state B at time T)*P(system in state B at time T)

Or to put it in simpler probability notation:

P(C) = P(C|A)*P(A) + P(C|B)*P(B)

But in certain QM experiments, if you do it this way you get the wrong answer for the probability of getting measurement result C when you measure at T' (an example would be the double-slit experiment, where the procedure above would lead you to expect the pattern on the screen would just be the sum of two single-slit interference patterns, when what you actually get is a different, double-slit interference pattern). So in the Schroedinger's cat thought-experiment, if you really want to see what's wrong with the assumption that the cat is definitely alive or dead at time T but you just don't know which, then you'd have to imagine something like waiting billions of years after T before opening the box, when the system has had enough time to go to maximum entropy so that all evidence of the cat's past history is lost by the time you open it, so you have no way to deduce whether it was alive or dead at time T. Then if you performed a sufficiently precise measurement of the quantum state of all the particles when you opened the box, the probability of finding them in some particular state S would not be given by what you'd expect given the assumption it was in a definite state at T, namely:

P(system in state S when box opened) = P(system in state S when box opened, given that the cat was alive at time T)*P(cat was alive at time T) + P(system in state S when box opened, given that the cat was dead at time T)*P(cat was dead at time T)

This doesn't necessarily prove that the cat wasn't definitely alive or dead at time T (in some 'hidden-variable' interpretations like Bohmian mechanics, it would definitely be one or the other), but if it was in a definite state, this implies that the probability the system will go to S at a much later time given that the cat was alive at T actually depends on whether or not the cat was measured by an external observer at time T or not.

 

[fromderinside]

When the detector in the box detects the decay the experiment is over. Who gives a shit about an outside observer? Irrelevant.

Ehh, if you don't know who won the match, and your buddy hasn't looked, you can still bet based on the knowledge you have. The QM knowledge is simply half-life in this case- if you make it so there is an even 50% chance that the atom decays, you're both idiots for making the bet, even more so for killing a fucking cat to make a bet. That's the relevance.

You don't know until you opened the box. Something definitely happened. The cat is definitely a fucking observer, as is the radiation detector, etc. There is no great fucking mystery- although maybe the universe, spacetime, God, or someone else reserves the right to choose paths 'til the last possible second.

Its an experiment that was changed when a camera was embedded inside the box making the outside observer irrelevant. The box is a metaphor for not having the capacity to measure something. Change the metaphor to a camera inside a box and neither the box nor the observer are necessary, Experiment over when camera records the decay (cat's death).

 

[Kharakov]

Ehh, if you don't know who won the match, and your buddy hasn't looked, you can still bet based on the knowledge you have. The QM knowledge is simply half-life in this case- if you make it so there is an even 50% chance that the atom decays, you're both idiots for making the bet, even more so for killing a fucking cat to make a bet. That's the relevance.

You don't know until you opened the box. Something definitely happened. The cat is definitely a fucking observer, as is the radiation detector, etc. There is no great fucking mystery- although maybe the universe, spacetime, God, or someone else reserves the right to choose paths 'til the last possible second.

Its an experiment that was changed when a camera was embedded inside the box making the outside observer irrelevant. The box is a metaphor for not having the capacity to measure something. Change the metaphor to a camera inside a box and neither the box nor the observer are necessary, Experiment over when camera records the decay (cat's death).

Betting isn't closed until the box is open. Now, if you want to influence the odds a bit... just stall.

 

[DBT]

Its an experiment that was changed when a camera was embedded inside the box making the outside observer irrelevant. The box is a metaphor for not having the capacity to measure something. Change the metaphor to a camera inside a box and neither the box nor the observer are necessary, Experiment over when camera records the decay (cat's death).

Betting isn't closed until the box is open. Now, if you want to influence the odds a bit... just stall.

Isn't the box essentially 'open' in the instance that the camera/recorder is imbedded and observing/recording?